This invention pertains to a mechanism usable in a formative orthodontic appliance. More specifically, it pertains to an adjustably-biasing, band-mounted mechanism joining pressure-applying members of such an appliance.
Orthodontics is a specialized field of dentistry which often involves the use of special appliances to be worn in a patient's mouth and to provide corrective forces to teeth to modify their relative positions or their orientations within the mouth. These appliances, commonly known as braces, include a wide diversity of treatment approaches other than the familiar wire-and-bracket assemblies. Two such approaches, commonly used in Europe for more than 50 years and more recently in the United States, involve the use of removable appliances or functional appliances.
Removable appliances typically include molded-acrylic sections contoured to fit against the hard palate in the case of upper jaw appliances, or to fit lingually on the lower dental arch in the case of lower jaw appliances. The acrylic sections form a base from which tooth pressure applying archwires, clasps, and the like extend to contact select teeth. Adjustment of the pressures from these acrylic sections is facilitated by manufacturing each section in two or more segments. Adjacent segments are joined with guide posts consisting of a pair of hollow cylinders in one segment and mated pistons in the other segment. An expansion screw assembly installed between the guide posts provides the necessary adjustment. An adjustment is usually made by first removing the acrylic section from the patient's mouth and then turning the expansion screw to change the appliance pressure as desired.
Functional appliances are usually more complex than removable appliances and are employed to correct upper and lower jaw relative positions as well as to modify tooth positions. These appliances also may include molded-acrylic sections, screws, wires, and clasps similar to removable appliances.
In typical orthodontic practice, treatment consists of installing an appliance in the patient's mouth and then making periodic adjustments to the appliance over a period of months, or even years, gradually to correct the condition under treatment. Appliances are categorized, inter alia, as being either fixed or removable. A fixed appliance is designed to be worn continuously by the patient and should be removed by the orthodontist only. A removable appliance is designed so that the patient may, himself or herself, remove all or part of the appliance to facilitate oral hygiene, to provide periodic respites from the treatment, or to make adjustments to the appliance.
Other forms of orthodontic appliances are available that utilize metallic tooth bands to which bracket structures and archwires are attached. One embodiment of prior art, as disclosed in U.S. Pat. No. 4,468,196, issued to Keller on Aug. 28, 1984, provides a tooth-pressure-applying mechanism in the form of an archwire attached to a tooth band with adjustably-biased coil spring means. As with other prior art devices, the archwire assembly of this device must be removed in order to make an adjustment thereto.
It is therefore a general object of the invention to provide access to the tooth pressure adjustment such that the adjustment may be made while the appliance is in place in the patient's mouth.
Another object of the invention is to reduce the bulk of the appliance required for a given treatment plan so that the appliance is not physically distracting and does not impair normal speech or oral hygiene.
A further object is to provide a fixed orthodontic appliance to be worn continuously, thereby reducing overall treatment time, and to eliminate, as a factor in treatment, patient cooperation in following a schedule having periodic installation intervals.
These and other objects and advantages which are attained by the invention will become manifest as the description which now follows is read in conjunction with the accompanying drawings.